Method and apparatus for making thermopile



8, wfi? E. A. JOERREN E L 3,335,043

METHOD AND APPARATUS FOR MAKING THERMOPILE Filed Feb. 1, 1961 2Sheets-Sheet 1 Aug. 1%? E. A. JOERREN ET AL fi METHOD AND APPARATUS FORMAKING THERMOPILE Filed Feb. 1, 1961 2 SheetsSheet i ATTORNEYS UnitedStates Patent 3,335,043 METHOD AND APPARATUS FOR MAKING THERMOPILEErnest A. Joerren, Brooklyn, N.Y., and Samuel M. Bagno,

Belleville, N.J., assignors to Specialties Development Corporation,Belleville, N.J., a corporation of New Jersey Filed Feb. 1, 1961, Ser.No. 86,339 8 Claims. (Cl. 156-269) The present invention relates tolengths of thermopile adapted for use in fire detecting systems, and,more particularly, to a thermopile strip which is an improvement overthat disclosed in copending application Serial No. 837,452, filedSeptember 1, 1959, assigned to the assignee of this application, nowPatent No. 3,018,311, January 23, 1962, and to apparatus and a methodfor making the same.

ing beyond the junction of the sections to provide intermediate portionshaving a junction thereon and being zigzag folded in a manner to providealternate hot and cold junctions on the folded strip.

The disadvantages with such strips are that the covering operation isdifficult and requires elaborate mechanism, the strip is difiicult toreel up after being folded, and about half of the strip structure is notused in its folded up condition.

Accordingly, the object of the present invention is to provide a simple,practical and economical manner of fabricating cheaper thermopile stripsby means of a rapid continuous process which can be carried out byrelatively simple apparatus and is not subject to the disadvantages-heretofore encountered in folding portions of the strip to producealternate hot and cold junctions.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment 1 about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings,forming a part of the specification, wherein:

FIG. 1 is a fragmentary plan view of a strip composed of dissimilarmetals which in response to heat generate an electromotive force.

FIG. 2 is a fragmentary plan view of the bi-metallic 'strip with a stripof insulating material applied to one side thereof.

FIG. 3 is a fragmentary plan view of the composite strip after beingformed with slots.

' FIG. 4 is a fragmentary plan view of the slotted composite strip aftercovering portions of the strip to provide alternate hot and coldjunctions.

FIG. 5 is an elevational view partly in section of apparatus includingrolls for covering portions of the strip.

FIG. 6 is a sectional view taken along the line 6-6 on FIG. 5.

FIG. 7 is an enlarged fragmentary elevational view of one of the rolls.

Referring first to FIGS. 1 to 4 of the drawings in detail, a strip 10 isshown in FIG. 1 which is composed of two lengthwise extending sections11 and 12, joined edgewise at 13, of dissimilar resistive metals such asnickel and iron, for example. This strip may have a thickness of about0.002 inch and a width of about one inch, and long lengths thereof canbe produced economically by butt welding suitably dimensioned blocks orbars of nickel and iron together and rolling down the composite block orbar to the desired thickness and width.

In FIG. 2, the strip 10 is shown after a layer 14 of thin paper or otherheat and electrical insulating material have been applied on one sidethereof.- The paper layer preferably is as wide as the strip but may beslightly wider than the strip with its edges evenly spaced from theedges of the strip. The primary purpose of the paper layer is to provideadequate covering or insulation at the back of the strip to enable hotand cold junctions to be established at the front of the strip. Thepaper layer 14 can be readily applied to the bi-metallic strip 10 byautomatic machinery (not shown) including roller means for adhesivelycoating the strip and/or the layer and roller means for pressing thestrip and the layer together to adhesively secure the same.

In FIG. 3, the composite bi-metallic and paper strip is shown afterforming substantially rectangular evenly spaced staggered slots 15 atopposite edges thereof. These slots extend widthwise beyond the junction13 of the metallic sections 11 and 12 to provide intermediate portions16 having a lengthwise dimension about equal to the lengthwise dimensionof the slots and edge sections 17 having a lengthwise dimension aboutthree times that of the intermediate portions. For example, a slotdimension of about 0.25 inch, an intermediate portion dimension of 0.25inch and an edge section dimension of 0.75. inch Y may be used.

In FIG. 4, the slotted strip is shown after covering alternateintermediate portions 16 with a film 18 of a mixture of finely dividedelectrically nonconductive, radiated heat insulating and heat reflectivematerial and an adhesive to thereby provide alternate exposed or hot andcovered or cold junctions h and c, and darkening the exposed or hotjunctions h with a stripe 19 of black paint or other heat absorbingmaterial to make the thermopile more sensitive to radiated heat.

The film mixture preferably comprises a slurry. of asbestos, magnesiumcarbonate and/or silica gel or the like, and any suitable quick dryingor heat dryable resin or adhesive for permanently securing the film 18on the strip over the cold junctions upon being dried.

In FIGS. 5 to 7, apparatus is shown for applying the film 18 whichgenerally comprises rolls 20 and 21 between which the slotted compositestrip (FIG. 3) passes, a tank 22 for a source of slurry 23, means forapplying slurry on the roll 21 such as a transfer roll 24 in con- 1 tactwith the roll 21 and passing through the source of slurry, and mechanismfor effecting rotation of the rolls including intermeshing gears 25, 26and 27 rotatable with the rolls 20, 21 and 24, respectively, and a motor28 having a gear 29 on its driveshaft in mesh with the gear 25.

In order to index the strip with respect to the rolls 20' and 21 andapply the slurry on the intermediate portions 16 to provide the film 18(FIG. 4), the roll 20' has staggered projections 30 at opposite edges ofits working surface which correspond in dimension and arrangement to theslots and are adapted to extend therethrough; and the roll 21 hassimilarly dimensioned and arranged recesses 31 on its working surfaceadapted to mesh with the projections 30 and has applicator surfaces 32between alternate pairs of recesses 31 corresponding in shape to thearea of the film 18 and adapted to contact the roll 24 to receive theslurry to be applied to the strip portions 16. The remainder of theworking surface of the roll 21 is provided with shallow recesses 34between adjacent surfaces 32 which correspond in shape to the portions16- of the strip to be left uncovered and remain out of contact with theroll 24 so that the slurry is not applied thereto. (FIGS. 6 and 7.)

While the apparatus has been described in connection with providing thefilm 18, the stripe of paint 19 could be applied in the same manner withalmost identical apparatus preferably after applying the film. Suchapparatus would be modified only in that the applicator surfaces 32would correspond in shape and position to stripe 19 and the shallowrecesses 34 would correspond in shape and position to the surfaces ofthe strip not to be coated with the paint.

In order to provide apparatus for continuous inline production of thethermopile, the metallic strip 10 and the backing strip 14 are firstunited and then passed through a pair of slotting rolls 35 and 36 havingpunch and counterpunch means 37 and 38 thereon corresponding in shapeand location to the projections 30 and the recesses 31 (FIG. 6). Theslotted composite strip is next passed through the film providing rollsand 21, is then passed through a pair of stripe providing rolls 39 and40 shown schematically, and is finally passed through a chamber (notshown) for thoroughly drying the file 18 and the stripe 19 beforereeling up the strip.

While the present invention has been illustrated and described withreference to a film-like covering composed of heat insulating materialand an adhesive, it will be understood that pieces of paper or the likehaving the same form as the film 18 could be adhesively applied to thestrip to accomplish the same result.

From the foregoing description, it will be seen that the presentinvention provides a simple, practical, rapid and economical manner ofproducing an improved thermopile strip.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in any limiting sense.

We claim:

1. The method of making a thermopile from a metallic strip composed oftwo edgewise joined lengthwise extending sections of metals havingdissimilar resistivities and having alternately staggered slots atopposite edges thereof extending beyond the junction of the sections toprovide intermediate portions having a junction thereon, which methodcomprises applying at one side of the metallic strip a coating of amixture of finely divided heat insulating material and an adhesive onalternate intermediate portions provided with a junction thereon toprovide a cold junction, indexing the metallic strip by means of theslots therein while applying the mixture to properly locate the coating,and drying the mixture to provide a covering secured to the strip.

2. The method of making a thermopile from a metallic strip composed oftwo edgewise joined lengthwise extending sections of metals havingdissimilar resistivities, which method comprises forming alternatelystaggered slots at opposite edges thereof extending beyond the junctionof the sections to provide intermediate portions having a junctionthereon, securing radiated heat insulating covering means at one side ofthe metallic strip on alternate intermediate portions provided with ajunction thereon to thereby provide alternate hot and cold junctions onthe metallic strip, the covering means being composed of a coating of amixture of finely divided heat Insulating material and an adhesive toprovide the cold junctions, and drying the mixture to provide a coveringsecured to the strip, said method including the step of indexing themetallic strip by means of the slots therein while applying the mixtureto properly locate the resulting covering on alternate intermediatepositions.

3. The method according to claim 2, which includes the step of firstapplying a backing strip to the metallic strip and slotting the samewith the metallic strip to facilitate indexing of the metallic strip.

4. Apparatus for applying a covering onto a thermopile strip composed oftwo edgewise joined sections of dissimilar metals having alternatelystaggered slots at opposite edges thereof extending beyond the junctionof the sections to provide intermediate portions having a junctionthereon, which apparatus comprises a first roll, having staggeredprojections at opposite edges thereof matching the slits of the stripand adapted to extend through the slots a second roll adjacent saidfirst roll having staggered recesses adapted to mesh with saidprojections to thereby index the strip between the rolls, said secondroll having applicator surfaces between alternate pairs of recesses forapplying the covering onto the strip at alternate intermediate portionsto provide cold junctions, means for applying the material providing thecovering onto said surfaces, and mechanism for effecting rotation ofsaid rolls to move the strip therebetween.

5. Apparatus according to claim 4, wherein said applying means includesa source of the covering material and a transfer roll passing throughsaid source and contacting said surfaces.

6. Apparatus according to claim 4, wherein said second roll has shallowrecesses between adjacent covering material applying surfaces which areineffective to apply the mixture to the strip.

7. Apparatus according to claim 6, wherein said shallow recesses andsaid surfaces correspond in shape to the surface area of the strip toremain uncoated and to be covered with the material.

8. In apparatus for producing a thermopile from .a strip composed of twoedgewise joined sections of dissimilar metals, the combination of a pairof rolls for forming alternately staggered slots at opposite edges ofthe strip extending beyond the junction of the sections to provideintermediate portions having a junction thereon, a means including apair of rolls for covering alternate intermediate portions with aradiated heat insulating material to provide cold junctions, and meansincluding a pair of rolls for striping the other intermediate portionswith a heat absorbing material to provide hot junctions, said pairs ofcovering and striping rolls having indexing means cooperating with theslots to position the portions of the strip to be covered or stripedwith respect to said covering and striping rolls.

References Cited UNITED STATES PATENTS 960,437 6/ 1910 Thompson 118211 X1,333,704 10/1917 Bushmeyer 83345 X 1,502,562 7/1924 Hausrath 136-2252,106,768 2/ 1938 Southworth 13622-5 X 2,211,707 8/1940 Sichere 118-372,278,744 4/1942 Sparrow et a1. 136-225 X 2,338,261 1/1944 Roth 1l8-372,381,819 8/1945 Graves et al. 136225 2,508,128 5/1950 Waards 1562542,519,785 8/1950 Okolicsanyi 136212 2,674,225 4/1954 Burke et a1 118211X 2,924,223 2/1960 Miller 83-345 X (Other references on following page)5 5/1960 Dunbar et a1. 117-4 10/ 1960 Wood 156-247 1/ 1962 Bagno et a1.136--225 9/ 1962 Nitchie 83-678 X OTHER REFERENCES Kimball et a1.,Optical Society of America, Journal, volume 7, 1923, pp. 707-13.

6 M011, A Thermopile for Measuring Radiation, Physi-

1. THE METHOD OF MAKING A THERMOPILE FROM A METALLIC STRIP COMPOSED OFTWO EDGEWISE JOINED LENGTHWISE EXTENDING SECTIONS OF METALSHAVINGDISSIMILAR RESISTIVES AND HAVING ALTERNATIVELY STAGGERED SLOTS ATOPPOSITE EDGES THEREOF EXTENDING BEYOND THE JUNCTION OF THE SECTIONS TOPROVIDE INTERMEDIATE PORTIONS HAVING A JUNCTION THEREON, WHICH METHODCOMPRISES APPLYING AT ONE SIDE OF THE METALLIC STRIP A COATING OF AMIXTURE OF FINELY DIVIDED HEAT INSULATING MATERIAL AND AN ADHESIVE ONALTERNATE INTERMEDIATE PORTIONS PROVIDED WITH A JUNCTION THEREON TOPROVIDE A COLD JUNCTION, INDEXING THE METALLIC STRIP BY MEANS OF THESLOTS THEREIN WHILE APPLYING THE MIXTURE TO PROPERLY LOCATE THE COATING,AND DRYING THE MIXTURE TO PROVIDE A COVERING SECURED TO THE STRIP. 2.THE METHOD OF MAKING A THERMOPILE FROM A METALLIC STRIP COMPOSED OF TWOEDGEWISE JOINED LENGTHWISE EXTENDING SECTIONS OF METALS HAVINGDISSIMILAR RESISTIVITIES, WHICH METHOD COMPRISES FORMING ALTERNATELYSTAGGERED SLOTS AT OPPOSITE EDGES THEREOF EXTENDING BEYOND THE JUNCTIONOF THE SECTIONS TO PROVIDE INTERMEDIATE PORTIONS HAVING A JUNCTIONTHEREON, SECURING RADIATED HEAT INSULATING COVERING MEANS AT ONE SIDE OFTHE METALLIC STRIP ON ALTERNATE INTERMEDIATE PORTIONS PROVIDED WITH AJUNCTION THEREON TO THEREBY PROVIDE ALTERNATE HOT AND COLD JUNCTIONS ONTHE METALLIC STRIP, THE COVERING MEANS BEING COMPOSED OF A COATING OF AMIXTURE OF FINELY DIVIDED HEAT INSULATING MATERIAL AND AN ADHESIVE TOPROVIDE THE COLD JUNCTIONS, AND DRYING THE MIXTURE TO PROVIDE A COVERINGSECURED TO THE STRIP, SAID METHOD INCLUDING THE STEP OF INDEXING THEMETALLIC STRIP BY MEANS OF THE SLOTS THEREIN WHILE APPLYING THE MIXTURETO PROPERLY LOCATE THE RESULTING COVERING ON ALTERNATE INTERMEDIATEPOSITIONS.
 3. THE METHOD ACCORDING TO CLAIM 2, WHICH INCLUDES THE STEPOF FIRST APPLYING A BACKING STRIP TO THE METALLIC STRIP AND SLOTTING THESAME WITH THE METALLIC STRIP TO FACILITATE INDEXING OF THE METALLICSTRIP.
 4. APPARATUS FOR APPLYING A COVERING ONTO A THERMOPILE STRIPCOMPOSED OF TWO EDGEWISE JOINED SECTIONS OF DISSIMILAR METALS HAVINGALTERNATELY STAGGERED SLOTS AT OPPOSITE EDGES THEREOF EXTENDING BEYONDTHE JUNCTION OF THE SECTIONS TO PROVIDE INTERMEDIATE PORTIONS HAVING AJUNCTION THEREON, WHICH APPARATUS COMPRISES A FIRST ROLL, HAVINGSTAGGERED PROJECTIONS AT OPPOSITE EDGES THEREOF MATCHING THE SLITS OFTHE STRIP AND ADAPTED TO EXTEND THROUGH THE SLOTS A SECOND ROLL ADJACENTSAID FIRST ROLL HAVING STAGGERED RECESSES ADAPTED TO MESH WITH SAIDPROJECTIONS TO THEREBY INDEX THE STRIP BETWEEN THE ROLLS, SAID SECONDROLL HAVING APPLICATOR SURFACES BETWEEN ATLERNATE PAIRS OF RECESSES FORAPPLYING THE COVERING ONTO THE STRIP AT ALTERNATE INTERMEDIATE PORTIONSTO PROVIDE COLD JUNCTIONS, MEANS FOR APPLYING THE MATERIAL PROVIDING THECOVERING ONTO SAID SURFACES, AND MECHANISM FOR EFFECTING ROTATION OFSAID ROLLS TO MOVE THE STRIP THEREBETWEEN.